CA1270805A - Process for preparation of synthetic mordenite molded body - Google Patents
Process for preparation of synthetic mordenite molded bodyInfo
- Publication number
- CA1270805A CA1270805A CA000518412A CA518412A CA1270805A CA 1270805 A CA1270805 A CA 1270805A CA 000518412 A CA000518412 A CA 000518412A CA 518412 A CA518412 A CA 518412A CA 1270805 A CA1270805 A CA 1270805A
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- CA
- Canada
- Prior art keywords
- molded body
- process according
- mordenite
- sodium silicate
- calcined
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/26—Aluminium-containing silicates, i.e. silico-aluminates
- C01B33/28—Base exchange silicates, e.g. zeolites
- C01B33/2807—Zeolitic silicoaluminates with a tridimensional crystalline structure possessing molecular sieve properties; Isomorphous compounds wherein a part of the aluminium ore of the silicon present may be replaced by other elements such as gallium, germanium, phosphorus; Preparation of zeolitic molecular sieves from molecular sieves of another type or from preformed reacting mixtures
- C01B33/2861—Zeolitic silicoaluminates with a tridimensional crystalline structure possessing molecular sieve properties; Isomorphous compounds wherein a part of the aluminium ore of the silicon present may be replaced by other elements such as gallium, germanium, phosphorus; Preparation of zeolitic molecular sieves from molecular sieves of another type or from preformed reacting mixtures of mordenite type, e.g. ptilolite or dachiardite
Abstract
PROCESS FOR PREPARATION OF SYNTHETIC
MORDENITE MOLDED BODY
ABSTRACT OF THE DISCLOSURE
A synthetic mordenite molded body is prepared by a process wherein a starting mixture comprising as the main components a silica source, an alumina source, an alkali source and water is molded into a starting molded body, the molded body is calcined and the calcined molded body is heated in an aqueous solution of sodium silicate. The starting mixture has incorporated therein a mordenite seed crystal powder. When the molded body is calcined, the temperature is elevated by heating to a calcination temperature not lower than 400°C at an average rate of at least 10°C/min and calcination is conducted at the calcination temperature within 2 hours.
When the calcined molded body is crystallized, an aqueous solution of sodium silicate having an SiO2 concentration of 7 to 25% by weight, an Na2O concentration of 2 to 8% by weight and an SiO2/Na2O molar ratio of from 0.9 to 4.0 is used as the aqueous solution of sodium silicate.
MORDENITE MOLDED BODY
ABSTRACT OF THE DISCLOSURE
A synthetic mordenite molded body is prepared by a process wherein a starting mixture comprising as the main components a silica source, an alumina source, an alkali source and water is molded into a starting molded body, the molded body is calcined and the calcined molded body is heated in an aqueous solution of sodium silicate. The starting mixture has incorporated therein a mordenite seed crystal powder. When the molded body is calcined, the temperature is elevated by heating to a calcination temperature not lower than 400°C at an average rate of at least 10°C/min and calcination is conducted at the calcination temperature within 2 hours.
When the calcined molded body is crystallized, an aqueous solution of sodium silicate having an SiO2 concentration of 7 to 25% by weight, an Na2O concentration of 2 to 8% by weight and an SiO2/Na2O molar ratio of from 0.9 to 4.0 is used as the aqueous solution of sodium silicate.
Description
PR ESS E'OR PREPARATION OF SYN~HETIC
r O DENITE MOLDED BODY
BACKGROUND OF THE INVENTION
1. Fie~d of the Invention The present invention relates to ~ process for the preparation of a synthetic mordenite molded body, in which a molded body of a starting mixture is first prepared and the molded body is calcined and then crystallized.
r O DENITE MOLDED BODY
BACKGROUND OF THE INVENTION
1. Fie~d of the Invention The present invention relates to ~ process for the preparation of a synthetic mordenite molded body, in which a molded body of a starting mixture is first prepared and the molded body is calcined and then crystallized.
2. Description of the Related Art Mordenite zeolite is a kind of a naturally produced zeolite, and various processes for synthesizing this zeolite have been proposed. Most of these proposals are directed to the production of mordenite crystal powdersO
When synthetic mo~denite is industrially utilized, use of a mordenite crystal powder is often difficult and it is ordinarily used after it has been molded into spheres, extrudates or other appropriate shapes.
However, since a zeolite crystal powder has no self-bondability, when a molded body is prepared, in order to impart appropriate plasticity and strength, an organic or inorganic binder is ordinarily used. As the incrganic binder, there can be mentioned clay minerals such as kaol~n and montmorillonite, and silica sol and alumina sol. However, often the mechanical strength of the thus prepared mordenite molded body is drastically reduced by a severe treatment such as an acid treatment or heat treatment in the process for forming a catalyst.
Furthermore, even if the mechanical strength is maintained at a certain level, the zeolite component is diluted by the added binder, and in order to impart a mechanical strength sufficient to resist industrial application, the amount of the binder should be ~'7~ 5 increased. Moreover, if a molded body of this type is used, sometîmes a calcination product of the binder such as a clay mineral cause~ an undesired side reaction.
Several processes in which a molded body of a starting mix-ture is formed instead of a molded body composed of ~ mixture of a mordenite powder and ~inders and the molded body is calcined and crystallized to obtain a synthetic mordenite molded body having sub-stantially the same shape as the shape before the crystallization have been proposed.
In these conventional processes, however, no special contrivance is made in the step of calcining the molded body or the step of withdrawing the synthetic mordenite molded body from a reaction vessel or washing this molded body after the crystallization. The calcination temperature and time for the molded body are only mentioned in Japanese Examined Patent Publications No. 40-la614 and No. 45-38975. In the process disclosed in Japanese Patent Publication No. 40-18614, a large amount of powdery mordenite is formed as a by-product in addition to a synthetic mordenite molded body and this powder adheres tightly to particles of the molded body.
Accoraingly, the particles of the molded body agglomerate to form a large mass, and withdrawal from the reaction vessel and washing become difficult.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to solve the problem of the prior art and to provide a process for the preparation of a synthetic mordenite 30 molded body, by which undesirable adhesion of a crystallized mordenite molded body by an aqueous solution of sodium silicate having a high viscosity and powdery mordenite formed as a by-product can be avoided, handling of the crystallized mordenite molded body can be performed very easily and safely, and a synthetic mordenite molded body having a high purity and a high crystallinity can be obtained.
~t~3~
In acco,rdance with the present invention, there is provided a process for the preparation of a synthetic mordenite mol,ded body, which comprises molding a starting mixture comprising as the main components a silica source, an alumina source, an alkali source and water (the obtained molded body is called "starting molaed body"), calcining the starting molded body (the obtained calcined body is called "calcined molded body"~ and heating the calcined molded body in an aqueous solution of sodium silicate (the obtained molded body is called "crystallized molded body"), said process being charac~
terized in that a mordenite seed crystal powder is made present in the starting mixture; when the starting molded body is calcined, the temperature is elevated by heating to a calcination temperature not lower than 400C at an average elevation rate of at least 10C/min and calcination is conducted at said calcination temper-ature within 2 hours; and when the calcined molded body is crystallized, an aqueous solution of sodium silicate having an Sio2 concentration of 7 to 25% by weight, an Na2O concentration of 2 to 8% by weight and an SiO2/Na2O
molar ratio of form 0.9 to 4.0 i5 used as the aqueous solution of sodium silicate.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a powder X-ray diffraction diagram of the synthetic mordenite molded body obtained in Example 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the instant specification, the average elevation rate of the temperature is expressed by the following formula:
(t' - to)/T
wherein t' stands for the calcination temper-ature (~C), to stands for the temperature (C) at which elevation of the temperature starts, and T stands for the time (minutes3 required for elevation to the calcination ~'7~3~
temperature from the point of the start of elevation of the temperature.
The starting ma~erials used in the presen~ invention are not particularly critical, and in the mixture of the starting materials, the SiO2/A12O3 molar ratio is from 9 to 30, preferably from 10 tO 20, and the Na2O/A12O3 molar ratio is 0.5 -to 7.5, preferably 0.5 to 2.
Accordingly, if the composition of the starting molded body and the composition of the crystallizing solution are appropriately selected, a high-silica mordenite molded body having an SiO2/A12O3 ratio of 12 to 30 can be pr~pared.
As the silica source, there can be used amorphous silica, silica sol, silica gel, sodium silicate, and naturally produced diatomaceous earth and silicate mineralsO Where a natural silica source is used, preferably impurities undesirable for the production of zeolite are removed in advance. As the alumina source, there can be used aluminum hydroxide, aluminum oxide, sodium aluminate, aluminum sulfate, aluminum nitrate, and naturally produced aluminosilicate minerals such as kaolinite and montmorillonite. When a natural silica or alumina source is used, the content of alumina or silica in the starting material must be taken into consideration for determining the above-mentioned composition. Sodium silicate or sodium alumina~e also acts as the alkali source. Sodium hydroxide may be used as the alkali source.
By making a mordenite seed crystal powder present in the starting material, the amount of powdery mordenite formed as a by-product can be reduced to less than 1/10 as compared with the case where the mordenite seed crystal powder is not present. Thus, the yield of the mordenite molded body can be improved and adhesion of molded bodies to one another by powdery mordenite can be greatly reduced.
Preferably the amount of the seed crystal powder ~ 3~3S
present in the starting mixture is 0.1 to 10~ by weight based on the starting mixture on the dry basis. If the amou~t of the seed crystal is sma]ler than 0O1% by weight, a substantial effect cannot be attained by the 5 adaition of the seed crystal, and i~ the amount of th~
seed crys~al exceeds 10% by weight, a further increase of the effect cannot be obtained. The effect is most prominent when the arnount of the seed crystal is 0.5 to 5~ by weight.
Good results are obtained when the particle diameter of the seed crys~al is a~out l ~m to about 5 ~m, but an agglomerate of crystal particles having scores of microns may be used. In this case, preferably the agglomerate is pulverized before it is used.
The seed crystal may be either natural mordenite or synthetic mordenite. Where synthetic mordenite is used, the SiO2/Al2O3 molar ratio may be within the range of from 10 to 30. Ordinarily, this molar ratio is adjusted to a value similar to that of the intended mordenite molded body. of course, no particular problem arises when synthetic morde~it~ having an SiO2/A12O3 molar ratio different from that of the intended mordenite molded body issued.
The effect of the seed crystal is prominent when the seed crystal is uniformly dispersed in the starting material mixture. The seed crystal may be added in the form of powder and mixed with the starting material powder or may be dispersed in water to be added to the starting material powder, or in sodium silicate. An optimum amount of water to be added differs according to the shape and size of the starting molded body or the kind of molding machine used for molding the starting mixture, but generally, this amount is in the range of from 40 to 120~ by weight based on the starting mixture on the dry basis. If the amount of water is too small and below this range, molding is very difficult, and if the amount of water is too large and exceeds the above-men~ioned range, the molded body is readily deformed ormutual adhesion of the molded body is caused.
The uniform starting material mixture is molded into a desired shape. When absorbents or catalysts are intended, the molded body is generally spheres or extrudates, but in other special use, the shape of the molded body is cylindrical, pillar, plate-like or honeycomb. This molded body can be obtained when the starting materials are combined within the above-mentioned range of the comp~sition.
In order to increase the viscosity and elasticityof the starting mixture and reduce the friction with the molding machine for improving the moldability at the molding step, carboxymethyl cellulose, stearic acid, alcohols, surface active agents or fibers may be added to the starting mixture as a molding assistant or lubricant.
An extruder, a tableting machine or a rotary molding machine is used as the molding machine according to the shape of the molded body.
The starting mixture molded into a desired shape, that is, the starting molded body, is then subjected to a calcination treatment. When an organic material is used as the molding assistant or an natural starting 25 materials are used, the starting molded body also contains this organic component. Especially when diatomaceous earth is used as the silica source, the amount of the organic component included in the starting molded body is large.
If the temperaturë-elevating rate is low at the calcining step, the organic component in the starting molded body is concentrated in the surface portion of the molded body and carbonized in the surace portion.
If carbon is precipitated on the surface of the calcined 35 molded body, surface exfoliation is caused in the molded body at the crystallizing step and the crystallized molded body fails to retain the shape of the calcined ()r molded body, with the result that a crystallized molded body havi~g a desired shape cannot be obtained On the other hand, if calcination is conducted at a high temperature for a long time for completely removing the organic component in the starting molded body, sintering of the molded body is advanced and the pore volume of the calcined molded body is reduced with the advance of the sintering.
In view of the relations of the temperature-elevating rate and calcination temperature at the time of calcination to the carbonization of the organic component in the startin~ molded body, the temperature is elevated to the calcination temperature at an average rate of at least 10C/min and the calcination carried out at a temperature not lower than 400C within 2 hours.
If the temperature is elevated at an average rate of at least 10C/min, the organic component in the starting molded body is uniformly decomposed without concentration in the surface portion or carbonization in the surface portion. The upper limit of the temper-ature-elevating rate is not particularly limited, but, is usually about 200C/min. In order to completely and uniformly decompose the organic component in the starting molded body and impart a practically sufficient mechani-cal strength to the crystallized molded body, thecalcination must be conducted at a temperature not ~ower than 400CC. However, if the calcination is carried out at too high a temperature, the reactivity is reduced because of vitrification of the starting molded body, and the pore volume is reduced. Accordingly, preferably the calcination is conducted at a temperature of 500 to 800C. Thus, the temperature elevation rate and the calcination temperature and time are satisfied, at the step of crystallizing the calcined molded body, such problems as surface exfoliation of the molded body, deformation of the calcined molded body and reduction of the pore volume in the calcined molded by advance of ~'7~
sintering of the starting molded body can be prevented.
Where a calcined molded body is prepared according to the above-mentioned procedures, even if crystalli-zation is effected in commercially available aqueous solution of sodium silicate No. 3 (SiO2 = 29.3% by weight, Na2O = 9.36% by weight~, by the action of the added seed crystal, the amount of powdery mordenite formed as a by-product is reduced to less than l/lo of the amount of powdery mordenite formed when the seed crystal is not added, and -the particle size of mordenite crystals in the synthetic mordenite molded body is small and when the molded body is formed into a catalyst, the effect of a steam treatment or the like is prominent.
Furthermore, by the effect of the above-mentioned calcining method, a synthetic mordenite molded body having a uniform shape and a sufficiently large pore volume can be obtained.
However, if commercially available aqueous solution of sodium silicate No. 3 is directly used as the crys-tallizing solution, the viscosity of the crystallizingsolution after the crystallization is drastically increased, and is further increased by cooling the reaction vessel, and this tendency is especially prominent in the vicinity of the outer surface of the synthetic mordenite molded body. Although formation of powdery mordenite is greatly decreased by the effect o~
the seed crystal, in the upper portion of the crystalli-zing packed layer, mutual adhesion of the molded body is still violent and handling is extremely difficult. At the subsequent washing step, a large quantity of warm water and a long time are necessary. More specifically, .he crystallized mordenite molded body is immersed in an aqueous solution of sodium silicate having a high viscosity, and the viscosity of the aqueous solution of sodium silicate is further increased when the reaction vessel is cooled. Accordingly, in order to efficiently separate the synthetic mordenite molded body from the 7~ 5 9 ~
aqueous solution of sodium si1icate, a difficult operation of T~ithdrawing the aqueous solution of sodium silicate at a high temperature under a high pressure becomes necessary.
S We carried out research with a view to eliminating this disadvantage, and found that when the sio2 concen-tration alone is reduced in the aqueous solution of sodium silicated used as the crystallizing solution, it is difficult to maintain the shape of the calcined molded body during the crystallization, and in an extreme case, it is quite impossible to maintain the shape of the molded body. It was also found that when the Na20 concentra~ion alone is reduced, the shape of the calcined molded b~dy can be maintained, but the crystallization is not sufficiently advanced and it is difficult to obtain a crystallized molded body having a high crystallinity, and when both of the SiO2 and Na2O
concentrations are reduced, also the SiO2/Na2O molar ratio is an important factor. Namely, it was found that when a crystallizing solution having a cvmposition described below is used, mutual adhesion of the molded body particles by powdery mordenite and highly viscous sodium silicate is not caused and handling is greatly facilitated.
More specifically, in the aqueous solution of sodium silicate used as the crystallizing solution in the present invention, the SiO2 concentration is 7 to 25~ by weight, preferably 7 to 12~ by weight, and the Na2O con centration iS 2 to 8~ by weight, preferably 2 to 6% by weight. It is preferred that the SiO2/Na2O molar ratio be from O . 9 to 4Ø The composition of the crystalli~ing solution is preferably within the above-mentionea range, irrespectively of the composition of the starting molded body. The amount of the aqueous solution of sodium silicate used is such that the calcined molded body placed in the vessel is completely immersed therein.
In carrying out the present invention, any material ~..~ 7(~
or mixing method may be adopted for controlling ~he SiO2 and Na2O concentra~ions and the SiO2/Na2Omolar ratio within the predetermined ranges. For example, there can be mentioned a method in which aqueous solution of sodium silicate No. 3 is diluted with pure water.
Accordinq to this rnethod, an aqueous solution of sodium silicate having low SiO2 andNa2O concentrations can be prepared relatively easily and economically advanta~eously without changin~ the SiO2/Na2O molar ratio in the a~ueous solution of sodium silicate.
Crystallization is carried out at 150 to 200C under an autogenous pressure preferably for 24 to 72 hours.
At the crystallizing step, stirring may be carried out if the rotation number is such that friction among molded body particles by rotation of the stirring vane or friction between the molded body and the stirring vane does not cause wear of the molded body.
After completion of the crystallization, the reaction vessel is cooled to room temperature by cooling water and the crystallized molded body is separated from the crystallizing solution, and the crystallized molded body is sufficiently washed with water or warm water and dried to obtain a sodium type ~ynthetic mordenite molded body.
As is apparent from the foregoing description, according to the present invention, since increase of the viscosity of the aqueous solution of sodium silicate or mutual adhesion of the molded body owing to formation of powdery mordenite is not caused after termination of the crystallization, handling of the crystallized molded body is very easy, and even at room temperature, the crystallized molded body can be separated from the crystallizing solution. Furthermore, when the SiO2 and Na20 concentrations in the crystallizing solutions are low, formation of powdery mordenite as a by-product is not caused at all. It is considered that this is because fo~mation of crystal nuclei of mordenite at the initial stage of the crystallization is depre~sed because of low SiO2 and Na2O concentrations in the crystallizing solution. Accordingly, mutual adhesion of the cryst~llized molded bod~ owing to ~owdery mordenite can be completely prevented. Moreover, when a dilut~d aqueous solution of sodium silicate is used as the crystallizing solution, the amount of aqueous solution of sodium silicate No. 3 used can be reduced, and the process becomes economically advantageous and a large quantity of water or warm water need not be used for washing the crystallized molded body.
Furthermore, the present invention is advantageous in that crystallization of a synthetic moldenite molded body under stirred conditions becomes possible, thou~h this is impossible in the conventional process for the preparation of a synthetic moldenite body. It is considered that this is because material transfer between the solution and the molded body is controlled.
This is very important from the industrial viewpoint.
When a zeolite is synthesized under stationary conditions, use of a large reaction vessel is not permissible, because the temperature distribution is very large in the reaction vessel, which renders formation of a zeolite having a high degree of crystalli-zation or a high purity difficult. As means for reducingthe temperature distribution, there may be considered a method in which the heat transfer area of the reaction vessel is increased. However, if the heat transfer area of the reaction vessel is increased, the structure of the reaction vessel becomes complicated and the reaction vessel is not preferred as an industrial preparation apparatus. In the present invention, since synthesis under stirring becomes possible, no contrivance need be made on the structure of the reaction apparatus for solving the problem of the heat conduction in increasing the scale of the reaction apparatus.
The synthetic mordenite molded body prepared according to the process of the present invention can adsor~ a sufficient quantity of benzene. Furthermore, even if this molded body is subjected to an ion exchange treatment, an acid treatment, a heat treatment or the like, the shape is maintained and the molded body has a mechanical strength sufficient to resist industrial applications.
Accordingly, the synthetic mordenite molded body can be used as an adsorbent as it is, and if the molded body is subjected to ion exchange with ammonium and is then calcined, a mordenite molded body of the H type can be obtained. Furthermore, an aluminum-removed ~-t~pe mordenite molded body obtained by repeating a mineral acid treatment and a heat treatment can be used as a solid acid catalyst for various reactions.
The present invention will now be described in detail with reference to the following examples.
Examples 1, 2 and 3 Compositions of Georgia kaolin, diatomaceous earth, an aqueous solution of sodium silicate (No. 3) and a seed crystal, used as the starting materials, are shown in Table 1.
Table 1 Ccmposition (~ by weight) A1203 Na20 H20 Georgia kaolin 46.26 38.46 0.22 13.76 Diatcrnaceous earth 83.70 3 .18 0.22 10.80 A~ueous solution of 29. 34 0. 02 9. 36 61.?8 sodium silicate (No. 3) Syn~hetic mordenite 68.65 11.50 6.81 11.98 seed crystal These starting materials were mixed at ratios shown in Table 2, and the mixture was sufficiently kneaded in a vertical stirring kneader. At this step, 6 g of ~ ~'7~ 5 calci~n stearate and 45 g of AVICEL in E~amples l and 3, and 135 g of AVICEL (crystalli1le cellulose) and 90 g of carbo~ymethyl cellulose in Example 2, were added as the granulating assistant The avera~e particle size of the synthetic mordenite added as the seed crystal was 7 ~m.
Table 2 ~n~ts tk~) added Aqueous solu Georgia Diatomaceous tion of sodium Seed Water kaolin_ earth silicate c~ystal EXample 1 l.40 2.64 4.06 0.26 0.20 E~le 2 1.22 3.07 1.84 0.22 2.30 EXample 3 1.40 2.64 4.06 0.26 0.20 The thus-obtained starting mixture was molded into extrudates having an outer diameter of l.8 mm in Examples l and 3 or into spheres having a diameter of 2 to 4 mm in Example 2. The starting molded body was dried at 100C for 2 hours and charged into a calcining furnace maintained at 650C. The temperature of the molded body was elevated from the atmospheric temperature to 650C
for 20 minutes. The molded body was maintained at this temperature for l hour. Then, 1 ~g of the thus obtained calcined molded body was cooled to room temperature, and the molded body was immersed in l.5 liters of an aqueous solution of sodium silicate having a composition shown in Table 3, heated at 180C for 48 hours and crystallized under an autogenous pressure.
* Trade mark , ,_.y ~3 ~t~3 Table 3 Sio2 contentNa2O content SiO2/Na2O
(~0 by~g~by wei~ht3 (m~lar ratio) _ E~ample 1 8.80 2.81 3.24 E~-ample 2 9.30 4.90 1.94 EXa~lple 3 17.60 5.62 3.24 After termination of the crystallization, the reaction vessel was cooled to room temperature. After a light shock was given to the outer side of the reaction vessel by a wood hammer, the crystallized molded body in the reaction vessel could be wi~hdrawn from the reactlon vesse~ by a water s~ream. The crystallized molded body had the same shape as that of the molded body before the crystalli~ation, and the shape was not disfigured at the step of withdrawing the molded body from the reaction vesselO The amount of powdery mordenite formed as a by-product at the withdrawing step was smaller than 1 g in Exampl~s 1 and 2, or 5 g in Example 3.
Each of the synthetic moraenite molded b~dies ohtained in Examples 1, 2 and 3 was pulverized and subjected to the x-ray diffractometry. It was found that each proauct was composed of mordenite free o~
impurities and having a high crystallinity.
A powder x-ray diffr~ction diagram of the synthetic mordenite molded body obtained in Example 1 is shown in Fig. 1.
Example 4 In the same manner as described in Example 1~ 36 kg of the calcined molded body was prepared. This molded body was charged in a large-scale reaction vessel having a capacity of 100 liters, and 54 liters of an aqueous solution of sodium silicate (SiOz = 8.80~ by weight, Na2O = 2.81~ by weight~ maintained at 60~C was poured into the reaction vessel. The temperature in the ~ 15 -reaction vessel was elevated to 180C over a period of 3 hours. Crystallization was carried out at 180~C under an autogenous pressure. S~irring of the calcinea molded body and crystallizing solution in the reaction vessel was started simultaneously with the starting of the elevation of the crystallizing solution and was stopped after the lapse of 5 hours.
After termination of the crystallization, the reaction vessel was cooled to room temperature by cooling water, and the crystallizing solution was withdrawn from the lower portion of the reaction vesselO
The crystalllzed molded body could be withdrawn from the reaction vessel only by a water stream without any shock being given to the reaction vessel. The thus-obtained crystallized m¢lded body retained the same shape aS that before the crystallization. From the results of the powder X-ray diffractometry, it was found that the crystallized molded body was composed of mordenite free of impurities and having a high crystallinity. When other physical properties were measured, it was found that, as shown in Table 4, the crystalli7ed molded body was a synthetic mordenite molded body which could be practically used.
Table 4 Chemical analysis ~molar ratio) s io 2/Al2O3 11.6 N220/Al203 1.02 BET specific surface area 349 m2/g Benzene zdsorption quantity 7.3 wt.%
(25C, 50 mmHg) Pore ~olume 0.23 cc/g Crushing strength 2.55 kg omparative Examples 1 and 2 The calcined molded body was prepared in the same manner as described in Example 1, and 1 kg of the calcined molded body was immersed in 1.5 liters of an aquecus solution of sodium silicate and sodium hydroxide having a composition shown in Table 5. The calcined molded body was maintained at 175C under an autogenous pressure for 48 hours.
Table 5 SiO2 content Na2O content SiO2/~a2O
(~ ky weight) (% by weight) ~m~lar ratio) ~xrative 29.34 9.36 3.24 Example 1 C~rative 0 3.80 Example 2 After termination of the crystallization, the reaction vessel was cooled to room temperature.
In Comparative Example 1, the crystallized molded body was obtained in the state immersed in the aqueous solution of sodium silicate having a high viscosity, and it was impossible to withdraw the crystallized molded body from the reaction vessel in the same manner as described in Example 1. Namely, it was impossible to withdraw the crystallized molded body without deformation. The amount of powdery mordenite formed as a by-product was 26 g. From the results of the powder X-ray diffractometry of the obtained crystallized molded body, it was found that the crystallized molded body was composed of mordenite free of impurities.
In Comparative Example 2, the calcined molded body failed to retain its shape after termination of the crystallization and the crystallized product was in the form of a slurry.
When synthetic mo~denite is industrially utilized, use of a mordenite crystal powder is often difficult and it is ordinarily used after it has been molded into spheres, extrudates or other appropriate shapes.
However, since a zeolite crystal powder has no self-bondability, when a molded body is prepared, in order to impart appropriate plasticity and strength, an organic or inorganic binder is ordinarily used. As the incrganic binder, there can be mentioned clay minerals such as kaol~n and montmorillonite, and silica sol and alumina sol. However, often the mechanical strength of the thus prepared mordenite molded body is drastically reduced by a severe treatment such as an acid treatment or heat treatment in the process for forming a catalyst.
Furthermore, even if the mechanical strength is maintained at a certain level, the zeolite component is diluted by the added binder, and in order to impart a mechanical strength sufficient to resist industrial application, the amount of the binder should be ~'7~ 5 increased. Moreover, if a molded body of this type is used, sometîmes a calcination product of the binder such as a clay mineral cause~ an undesired side reaction.
Several processes in which a molded body of a starting mix-ture is formed instead of a molded body composed of ~ mixture of a mordenite powder and ~inders and the molded body is calcined and crystallized to obtain a synthetic mordenite molded body having sub-stantially the same shape as the shape before the crystallization have been proposed.
In these conventional processes, however, no special contrivance is made in the step of calcining the molded body or the step of withdrawing the synthetic mordenite molded body from a reaction vessel or washing this molded body after the crystallization. The calcination temperature and time for the molded body are only mentioned in Japanese Examined Patent Publications No. 40-la614 and No. 45-38975. In the process disclosed in Japanese Patent Publication No. 40-18614, a large amount of powdery mordenite is formed as a by-product in addition to a synthetic mordenite molded body and this powder adheres tightly to particles of the molded body.
Accoraingly, the particles of the molded body agglomerate to form a large mass, and withdrawal from the reaction vessel and washing become difficult.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to solve the problem of the prior art and to provide a process for the preparation of a synthetic mordenite 30 molded body, by which undesirable adhesion of a crystallized mordenite molded body by an aqueous solution of sodium silicate having a high viscosity and powdery mordenite formed as a by-product can be avoided, handling of the crystallized mordenite molded body can be performed very easily and safely, and a synthetic mordenite molded body having a high purity and a high crystallinity can be obtained.
~t~3~
In acco,rdance with the present invention, there is provided a process for the preparation of a synthetic mordenite mol,ded body, which comprises molding a starting mixture comprising as the main components a silica source, an alumina source, an alkali source and water (the obtained molded body is called "starting molaed body"), calcining the starting molded body (the obtained calcined body is called "calcined molded body"~ and heating the calcined molded body in an aqueous solution of sodium silicate (the obtained molded body is called "crystallized molded body"), said process being charac~
terized in that a mordenite seed crystal powder is made present in the starting mixture; when the starting molded body is calcined, the temperature is elevated by heating to a calcination temperature not lower than 400C at an average elevation rate of at least 10C/min and calcination is conducted at said calcination temper-ature within 2 hours; and when the calcined molded body is crystallized, an aqueous solution of sodium silicate having an Sio2 concentration of 7 to 25% by weight, an Na2O concentration of 2 to 8% by weight and an SiO2/Na2O
molar ratio of form 0.9 to 4.0 i5 used as the aqueous solution of sodium silicate.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a powder X-ray diffraction diagram of the synthetic mordenite molded body obtained in Example 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the instant specification, the average elevation rate of the temperature is expressed by the following formula:
(t' - to)/T
wherein t' stands for the calcination temper-ature (~C), to stands for the temperature (C) at which elevation of the temperature starts, and T stands for the time (minutes3 required for elevation to the calcination ~'7~3~
temperature from the point of the start of elevation of the temperature.
The starting ma~erials used in the presen~ invention are not particularly critical, and in the mixture of the starting materials, the SiO2/A12O3 molar ratio is from 9 to 30, preferably from 10 tO 20, and the Na2O/A12O3 molar ratio is 0.5 -to 7.5, preferably 0.5 to 2.
Accordingly, if the composition of the starting molded body and the composition of the crystallizing solution are appropriately selected, a high-silica mordenite molded body having an SiO2/A12O3 ratio of 12 to 30 can be pr~pared.
As the silica source, there can be used amorphous silica, silica sol, silica gel, sodium silicate, and naturally produced diatomaceous earth and silicate mineralsO Where a natural silica source is used, preferably impurities undesirable for the production of zeolite are removed in advance. As the alumina source, there can be used aluminum hydroxide, aluminum oxide, sodium aluminate, aluminum sulfate, aluminum nitrate, and naturally produced aluminosilicate minerals such as kaolinite and montmorillonite. When a natural silica or alumina source is used, the content of alumina or silica in the starting material must be taken into consideration for determining the above-mentioned composition. Sodium silicate or sodium alumina~e also acts as the alkali source. Sodium hydroxide may be used as the alkali source.
By making a mordenite seed crystal powder present in the starting material, the amount of powdery mordenite formed as a by-product can be reduced to less than 1/10 as compared with the case where the mordenite seed crystal powder is not present. Thus, the yield of the mordenite molded body can be improved and adhesion of molded bodies to one another by powdery mordenite can be greatly reduced.
Preferably the amount of the seed crystal powder ~ 3~3S
present in the starting mixture is 0.1 to 10~ by weight based on the starting mixture on the dry basis. If the amou~t of the seed crystal is sma]ler than 0O1% by weight, a substantial effect cannot be attained by the 5 adaition of the seed crystal, and i~ the amount of th~
seed crys~al exceeds 10% by weight, a further increase of the effect cannot be obtained. The effect is most prominent when the arnount of the seed crystal is 0.5 to 5~ by weight.
Good results are obtained when the particle diameter of the seed crys~al is a~out l ~m to about 5 ~m, but an agglomerate of crystal particles having scores of microns may be used. In this case, preferably the agglomerate is pulverized before it is used.
The seed crystal may be either natural mordenite or synthetic mordenite. Where synthetic mordenite is used, the SiO2/Al2O3 molar ratio may be within the range of from 10 to 30. Ordinarily, this molar ratio is adjusted to a value similar to that of the intended mordenite molded body. of course, no particular problem arises when synthetic morde~it~ having an SiO2/A12O3 molar ratio different from that of the intended mordenite molded body issued.
The effect of the seed crystal is prominent when the seed crystal is uniformly dispersed in the starting material mixture. The seed crystal may be added in the form of powder and mixed with the starting material powder or may be dispersed in water to be added to the starting material powder, or in sodium silicate. An optimum amount of water to be added differs according to the shape and size of the starting molded body or the kind of molding machine used for molding the starting mixture, but generally, this amount is in the range of from 40 to 120~ by weight based on the starting mixture on the dry basis. If the amount of water is too small and below this range, molding is very difficult, and if the amount of water is too large and exceeds the above-men~ioned range, the molded body is readily deformed ormutual adhesion of the molded body is caused.
The uniform starting material mixture is molded into a desired shape. When absorbents or catalysts are intended, the molded body is generally spheres or extrudates, but in other special use, the shape of the molded body is cylindrical, pillar, plate-like or honeycomb. This molded body can be obtained when the starting materials are combined within the above-mentioned range of the comp~sition.
In order to increase the viscosity and elasticityof the starting mixture and reduce the friction with the molding machine for improving the moldability at the molding step, carboxymethyl cellulose, stearic acid, alcohols, surface active agents or fibers may be added to the starting mixture as a molding assistant or lubricant.
An extruder, a tableting machine or a rotary molding machine is used as the molding machine according to the shape of the molded body.
The starting mixture molded into a desired shape, that is, the starting molded body, is then subjected to a calcination treatment. When an organic material is used as the molding assistant or an natural starting 25 materials are used, the starting molded body also contains this organic component. Especially when diatomaceous earth is used as the silica source, the amount of the organic component included in the starting molded body is large.
If the temperaturë-elevating rate is low at the calcining step, the organic component in the starting molded body is concentrated in the surface portion of the molded body and carbonized in the surace portion.
If carbon is precipitated on the surface of the calcined 35 molded body, surface exfoliation is caused in the molded body at the crystallizing step and the crystallized molded body fails to retain the shape of the calcined ()r molded body, with the result that a crystallized molded body havi~g a desired shape cannot be obtained On the other hand, if calcination is conducted at a high temperature for a long time for completely removing the organic component in the starting molded body, sintering of the molded body is advanced and the pore volume of the calcined molded body is reduced with the advance of the sintering.
In view of the relations of the temperature-elevating rate and calcination temperature at the time of calcination to the carbonization of the organic component in the startin~ molded body, the temperature is elevated to the calcination temperature at an average rate of at least 10C/min and the calcination carried out at a temperature not lower than 400C within 2 hours.
If the temperature is elevated at an average rate of at least 10C/min, the organic component in the starting molded body is uniformly decomposed without concentration in the surface portion or carbonization in the surface portion. The upper limit of the temper-ature-elevating rate is not particularly limited, but, is usually about 200C/min. In order to completely and uniformly decompose the organic component in the starting molded body and impart a practically sufficient mechani-cal strength to the crystallized molded body, thecalcination must be conducted at a temperature not ~ower than 400CC. However, if the calcination is carried out at too high a temperature, the reactivity is reduced because of vitrification of the starting molded body, and the pore volume is reduced. Accordingly, preferably the calcination is conducted at a temperature of 500 to 800C. Thus, the temperature elevation rate and the calcination temperature and time are satisfied, at the step of crystallizing the calcined molded body, such problems as surface exfoliation of the molded body, deformation of the calcined molded body and reduction of the pore volume in the calcined molded by advance of ~'7~
sintering of the starting molded body can be prevented.
Where a calcined molded body is prepared according to the above-mentioned procedures, even if crystalli-zation is effected in commercially available aqueous solution of sodium silicate No. 3 (SiO2 = 29.3% by weight, Na2O = 9.36% by weight~, by the action of the added seed crystal, the amount of powdery mordenite formed as a by-product is reduced to less than l/lo of the amount of powdery mordenite formed when the seed crystal is not added, and -the particle size of mordenite crystals in the synthetic mordenite molded body is small and when the molded body is formed into a catalyst, the effect of a steam treatment or the like is prominent.
Furthermore, by the effect of the above-mentioned calcining method, a synthetic mordenite molded body having a uniform shape and a sufficiently large pore volume can be obtained.
However, if commercially available aqueous solution of sodium silicate No. 3 is directly used as the crys-tallizing solution, the viscosity of the crystallizingsolution after the crystallization is drastically increased, and is further increased by cooling the reaction vessel, and this tendency is especially prominent in the vicinity of the outer surface of the synthetic mordenite molded body. Although formation of powdery mordenite is greatly decreased by the effect o~
the seed crystal, in the upper portion of the crystalli-zing packed layer, mutual adhesion of the molded body is still violent and handling is extremely difficult. At the subsequent washing step, a large quantity of warm water and a long time are necessary. More specifically, .he crystallized mordenite molded body is immersed in an aqueous solution of sodium silicate having a high viscosity, and the viscosity of the aqueous solution of sodium silicate is further increased when the reaction vessel is cooled. Accordingly, in order to efficiently separate the synthetic mordenite molded body from the 7~ 5 9 ~
aqueous solution of sodium si1icate, a difficult operation of T~ithdrawing the aqueous solution of sodium silicate at a high temperature under a high pressure becomes necessary.
S We carried out research with a view to eliminating this disadvantage, and found that when the sio2 concen-tration alone is reduced in the aqueous solution of sodium silicated used as the crystallizing solution, it is difficult to maintain the shape of the calcined molded body during the crystallization, and in an extreme case, it is quite impossible to maintain the shape of the molded body. It was also found that when the Na20 concentra~ion alone is reduced, the shape of the calcined molded b~dy can be maintained, but the crystallization is not sufficiently advanced and it is difficult to obtain a crystallized molded body having a high crystallinity, and when both of the SiO2 and Na2O
concentrations are reduced, also the SiO2/Na2O molar ratio is an important factor. Namely, it was found that when a crystallizing solution having a cvmposition described below is used, mutual adhesion of the molded body particles by powdery mordenite and highly viscous sodium silicate is not caused and handling is greatly facilitated.
More specifically, in the aqueous solution of sodium silicate used as the crystallizing solution in the present invention, the SiO2 concentration is 7 to 25~ by weight, preferably 7 to 12~ by weight, and the Na2O con centration iS 2 to 8~ by weight, preferably 2 to 6% by weight. It is preferred that the SiO2/Na2O molar ratio be from O . 9 to 4Ø The composition of the crystalli~ing solution is preferably within the above-mentionea range, irrespectively of the composition of the starting molded body. The amount of the aqueous solution of sodium silicate used is such that the calcined molded body placed in the vessel is completely immersed therein.
In carrying out the present invention, any material ~..~ 7(~
or mixing method may be adopted for controlling ~he SiO2 and Na2O concentra~ions and the SiO2/Na2Omolar ratio within the predetermined ranges. For example, there can be mentioned a method in which aqueous solution of sodium silicate No. 3 is diluted with pure water.
Accordinq to this rnethod, an aqueous solution of sodium silicate having low SiO2 andNa2O concentrations can be prepared relatively easily and economically advanta~eously without changin~ the SiO2/Na2O molar ratio in the a~ueous solution of sodium silicate.
Crystallization is carried out at 150 to 200C under an autogenous pressure preferably for 24 to 72 hours.
At the crystallizing step, stirring may be carried out if the rotation number is such that friction among molded body particles by rotation of the stirring vane or friction between the molded body and the stirring vane does not cause wear of the molded body.
After completion of the crystallization, the reaction vessel is cooled to room temperature by cooling water and the crystallized molded body is separated from the crystallizing solution, and the crystallized molded body is sufficiently washed with water or warm water and dried to obtain a sodium type ~ynthetic mordenite molded body.
As is apparent from the foregoing description, according to the present invention, since increase of the viscosity of the aqueous solution of sodium silicate or mutual adhesion of the molded body owing to formation of powdery mordenite is not caused after termination of the crystallization, handling of the crystallized molded body is very easy, and even at room temperature, the crystallized molded body can be separated from the crystallizing solution. Furthermore, when the SiO2 and Na20 concentrations in the crystallizing solutions are low, formation of powdery mordenite as a by-product is not caused at all. It is considered that this is because fo~mation of crystal nuclei of mordenite at the initial stage of the crystallization is depre~sed because of low SiO2 and Na2O concentrations in the crystallizing solution. Accordingly, mutual adhesion of the cryst~llized molded bod~ owing to ~owdery mordenite can be completely prevented. Moreover, when a dilut~d aqueous solution of sodium silicate is used as the crystallizing solution, the amount of aqueous solution of sodium silicate No. 3 used can be reduced, and the process becomes economically advantageous and a large quantity of water or warm water need not be used for washing the crystallized molded body.
Furthermore, the present invention is advantageous in that crystallization of a synthetic moldenite molded body under stirred conditions becomes possible, thou~h this is impossible in the conventional process for the preparation of a synthetic moldenite body. It is considered that this is because material transfer between the solution and the molded body is controlled.
This is very important from the industrial viewpoint.
When a zeolite is synthesized under stationary conditions, use of a large reaction vessel is not permissible, because the temperature distribution is very large in the reaction vessel, which renders formation of a zeolite having a high degree of crystalli-zation or a high purity difficult. As means for reducingthe temperature distribution, there may be considered a method in which the heat transfer area of the reaction vessel is increased. However, if the heat transfer area of the reaction vessel is increased, the structure of the reaction vessel becomes complicated and the reaction vessel is not preferred as an industrial preparation apparatus. In the present invention, since synthesis under stirring becomes possible, no contrivance need be made on the structure of the reaction apparatus for solving the problem of the heat conduction in increasing the scale of the reaction apparatus.
The synthetic mordenite molded body prepared according to the process of the present invention can adsor~ a sufficient quantity of benzene. Furthermore, even if this molded body is subjected to an ion exchange treatment, an acid treatment, a heat treatment or the like, the shape is maintained and the molded body has a mechanical strength sufficient to resist industrial applications.
Accordingly, the synthetic mordenite molded body can be used as an adsorbent as it is, and if the molded body is subjected to ion exchange with ammonium and is then calcined, a mordenite molded body of the H type can be obtained. Furthermore, an aluminum-removed ~-t~pe mordenite molded body obtained by repeating a mineral acid treatment and a heat treatment can be used as a solid acid catalyst for various reactions.
The present invention will now be described in detail with reference to the following examples.
Examples 1, 2 and 3 Compositions of Georgia kaolin, diatomaceous earth, an aqueous solution of sodium silicate (No. 3) and a seed crystal, used as the starting materials, are shown in Table 1.
Table 1 Ccmposition (~ by weight) A1203 Na20 H20 Georgia kaolin 46.26 38.46 0.22 13.76 Diatcrnaceous earth 83.70 3 .18 0.22 10.80 A~ueous solution of 29. 34 0. 02 9. 36 61.?8 sodium silicate (No. 3) Syn~hetic mordenite 68.65 11.50 6.81 11.98 seed crystal These starting materials were mixed at ratios shown in Table 2, and the mixture was sufficiently kneaded in a vertical stirring kneader. At this step, 6 g of ~ ~'7~ 5 calci~n stearate and 45 g of AVICEL in E~amples l and 3, and 135 g of AVICEL (crystalli1le cellulose) and 90 g of carbo~ymethyl cellulose in Example 2, were added as the granulating assistant The avera~e particle size of the synthetic mordenite added as the seed crystal was 7 ~m.
Table 2 ~n~ts tk~) added Aqueous solu Georgia Diatomaceous tion of sodium Seed Water kaolin_ earth silicate c~ystal EXample 1 l.40 2.64 4.06 0.26 0.20 E~le 2 1.22 3.07 1.84 0.22 2.30 EXample 3 1.40 2.64 4.06 0.26 0.20 The thus-obtained starting mixture was molded into extrudates having an outer diameter of l.8 mm in Examples l and 3 or into spheres having a diameter of 2 to 4 mm in Example 2. The starting molded body was dried at 100C for 2 hours and charged into a calcining furnace maintained at 650C. The temperature of the molded body was elevated from the atmospheric temperature to 650C
for 20 minutes. The molded body was maintained at this temperature for l hour. Then, 1 ~g of the thus obtained calcined molded body was cooled to room temperature, and the molded body was immersed in l.5 liters of an aqueous solution of sodium silicate having a composition shown in Table 3, heated at 180C for 48 hours and crystallized under an autogenous pressure.
* Trade mark , ,_.y ~3 ~t~3 Table 3 Sio2 contentNa2O content SiO2/Na2O
(~0 by~g~by wei~ht3 (m~lar ratio) _ E~ample 1 8.80 2.81 3.24 E~-ample 2 9.30 4.90 1.94 EXa~lple 3 17.60 5.62 3.24 After termination of the crystallization, the reaction vessel was cooled to room temperature. After a light shock was given to the outer side of the reaction vessel by a wood hammer, the crystallized molded body in the reaction vessel could be wi~hdrawn from the reactlon vesse~ by a water s~ream. The crystallized molded body had the same shape as that of the molded body before the crystalli~ation, and the shape was not disfigured at the step of withdrawing the molded body from the reaction vesselO The amount of powdery mordenite formed as a by-product at the withdrawing step was smaller than 1 g in Exampl~s 1 and 2, or 5 g in Example 3.
Each of the synthetic moraenite molded b~dies ohtained in Examples 1, 2 and 3 was pulverized and subjected to the x-ray diffractometry. It was found that each proauct was composed of mordenite free o~
impurities and having a high crystallinity.
A powder x-ray diffr~ction diagram of the synthetic mordenite molded body obtained in Example 1 is shown in Fig. 1.
Example 4 In the same manner as described in Example 1~ 36 kg of the calcined molded body was prepared. This molded body was charged in a large-scale reaction vessel having a capacity of 100 liters, and 54 liters of an aqueous solution of sodium silicate (SiOz = 8.80~ by weight, Na2O = 2.81~ by weight~ maintained at 60~C was poured into the reaction vessel. The temperature in the ~ 15 -reaction vessel was elevated to 180C over a period of 3 hours. Crystallization was carried out at 180~C under an autogenous pressure. S~irring of the calcinea molded body and crystallizing solution in the reaction vessel was started simultaneously with the starting of the elevation of the crystallizing solution and was stopped after the lapse of 5 hours.
After termination of the crystallization, the reaction vessel was cooled to room temperature by cooling water, and the crystallizing solution was withdrawn from the lower portion of the reaction vesselO
The crystalllzed molded body could be withdrawn from the reaction vessel only by a water stream without any shock being given to the reaction vessel. The thus-obtained crystallized m¢lded body retained the same shape aS that before the crystallization. From the results of the powder X-ray diffractometry, it was found that the crystallized molded body was composed of mordenite free of impurities and having a high crystallinity. When other physical properties were measured, it was found that, as shown in Table 4, the crystalli7ed molded body was a synthetic mordenite molded body which could be practically used.
Table 4 Chemical analysis ~molar ratio) s io 2/Al2O3 11.6 N220/Al203 1.02 BET specific surface area 349 m2/g Benzene zdsorption quantity 7.3 wt.%
(25C, 50 mmHg) Pore ~olume 0.23 cc/g Crushing strength 2.55 kg omparative Examples 1 and 2 The calcined molded body was prepared in the same manner as described in Example 1, and 1 kg of the calcined molded body was immersed in 1.5 liters of an aquecus solution of sodium silicate and sodium hydroxide having a composition shown in Table 5. The calcined molded body was maintained at 175C under an autogenous pressure for 48 hours.
Table 5 SiO2 content Na2O content SiO2/~a2O
(~ ky weight) (% by weight) ~m~lar ratio) ~xrative 29.34 9.36 3.24 Example 1 C~rative 0 3.80 Example 2 After termination of the crystallization, the reaction vessel was cooled to room temperature.
In Comparative Example 1, the crystallized molded body was obtained in the state immersed in the aqueous solution of sodium silicate having a high viscosity, and it was impossible to withdraw the crystallized molded body from the reaction vessel in the same manner as described in Example 1. Namely, it was impossible to withdraw the crystallized molded body without deformation. The amount of powdery mordenite formed as a by-product was 26 g. From the results of the powder X-ray diffractometry of the obtained crystallized molded body, it was found that the crystallized molded body was composed of mordenite free of impurities.
In Comparative Example 2, the calcined molded body failed to retain its shape after termination of the crystallization and the crystallized product was in the form of a slurry.
Claims (13)
1. An improvement in a process for the preparation of a synthetic mordenite molded body, which comprises molding a starting mixture comprising as the main components a silica source, an alumina source, an alkali source and water to obtain a starting molded body, calcining the molded body to obtain a calcined molded body and heating the calcined molded body in an aqueous solution of sodium silicate, the improvement comprising (a) making a mordenite seed crystal powder present in the starting mixture, (b) when the starting molded body is calcined, elevating the temperature by heating to a calcination temperature not lower than 400°C at an average elevation rate of at least 10°C/min and carrying out the calcination at said calcination temperature within 2 hours, and (c) when the calcined molded body is crystallized, using an aqueous solution of sodium silicate having an SiO2 concentration of 7 to 25% by weight, an Na2O concentration of 2 to 8% by weight and an SiO2/Na2O molar ratio of from 0.9 to 4.0 as the aqueous solution of sodium silicate.
2. The process according to claim 1, wherein the starting mixture has an SiO2/Al2O3 molar ratio of 9 to 30 and an Na2O/Al2O3 molar ratio of 0.5 to 7.5.
3. The process according to claim 1, wherein the starting mixture has an SiO2/Al2O3 molar ratio of 10 to 20 and an Na2O/Al2O3 molar ratio of 0.5 to 2.
4. The process according to claim 1, wherein the alumina source is selected from the group consisting of aluminum hydroxide, aluminum oxide, sodium aluminate, aluminum sulfate, aluminum nitrate, kaolinite and montmorillonite.
5. The process according to claim 1, wherein the silica source is selected from the group consisting of amorphous silica, silica sol, silica gel, sodium silicate, diatomaceous earth and silicate minerals.
6. The process according to claim 1, wherein the alkali source is selected from the group consisting of sodium hydroxide, sodium silicate and sodium aluminate.
7. The process according to claim l, wherein the amount of the mordenite seed crystal powder is 0.1 to 10% by weight based on the starting mixture on the dry basis.
8. The process according to claim 1, wherein the amount of the mordenite seed crystal powder is 0.5 to 5 by weight based on the starting mixture on the dry basis.
9. The process according to claim 1, wherein the mordenite seed crystal powder has a particle diameter of about 1 µm to about 5 µm.
10. The process according to claim 1, wherein the amount of water in the stating mixture is from 40 to 120% by weight based on the starting mixture on the dry basis.
11. The process according to claim 1, wherein the calcination temperature is from 500°C to 800°C.
12. The process according to claim 1, wherein the aqueous solution of sodium silicate has an SiO2 concen-tration of 7 to 12% by weight and an Na2O concentration of 2 to 6% by weight.
13. The process according to claim 1, wherein the crystallization is effected at a temperature of 150 to 200°C under an autogenous pressure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60206637A JPH0672011B2 (en) | 1985-09-20 | 1985-09-20 | Method for producing synthetic mordenite compact |
| JP60-206637 | 1985-09-20 |
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| Publication Number | Publication Date |
|---|---|
| CA1270805A true CA1270805A (en) | 1990-06-26 |
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| CA000518412A Expired CA1270805A (en) | 1985-09-20 | 1986-09-17 | Process for preparation of synthetic mordenite molded body |
Country Status (7)
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| US (1) | US4861571A (en) |
| EP (1) | EP0216312B1 (en) |
| JP (1) | JPH0672011B2 (en) |
| AU (1) | AU586281B2 (en) |
| CA (1) | CA1270805A (en) |
| DE (1) | DE3670276D1 (en) |
| DK (1) | DK166723B1 (en) |
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| US5271914A (en) * | 1990-04-04 | 1993-12-21 | Tosoh Corporation | Process for adsorbing the vapor of alcoholic fuels |
| GB9101456D0 (en) * | 1991-01-23 | 1991-03-06 | Exxon Chemical Patents Inc | Process for producing substantially binder-free zeolite |
| DE69511575T2 (en) * | 1994-11-23 | 2000-04-27 | Exxon Chemical Patents Inc | METHOD FOR CONVERTING HYDROCARBONS USING A ZEOLITE CATALYZER TIED BY ZEOLITH |
| US5919430A (en) | 1996-06-19 | 1999-07-06 | Degussa Aktiengesellschaft | Preparation of crystalline microporous and mesoporous metal silicates, products produced thereby and use thereof |
| US6395070B1 (en) * | 1998-10-06 | 2002-05-28 | Matheson Tri-Gas, Inc. | Methods for removal of impurity metals from gases using low metal zeolites |
| US6110258A (en) * | 1998-10-06 | 2000-08-29 | Matheson Tri-Gas, Inc. | Methods for removal of water from gases using superheated zeolites |
| JP2007526772A (en) * | 2004-02-27 | 2007-09-20 | プレジデント・アンド・フェロウズ・オブ・ハーバード・カレッジ | Polony fluorescent beads for in situ sequencing |
| US20100047876A1 (en) * | 2008-08-08 | 2010-02-25 | President And Fellows Of Harvard College | Hierarchical assembly of polynucleotides |
| US9902950B2 (en) | 2010-10-08 | 2018-02-27 | President And Fellows Of Harvard College | High-throughput single cell barcoding |
| EP2766498B1 (en) | 2011-10-14 | 2019-06-19 | President and Fellows of Harvard College | Sequencing by structure assembly |
| CN103084156A (en) | 2011-11-04 | 2013-05-08 | 财团法人工业技术研究院 | Dehumidification device and electrifying desorption device thereof |
| WO2013184754A2 (en) | 2012-06-05 | 2013-12-12 | President And Fellows Of Harvard College | Spatial sequencing of nucleic acids using dna origami probes |
| CN108875312A (en) | 2012-07-19 | 2018-11-23 | 哈佛大学校长及研究员协会 | Utilize the method for nucleic acid storage information |
| US9476089B2 (en) | 2012-10-18 | 2016-10-25 | President And Fellows Of Harvard College | Methods of making oligonucleotide probes |
| US10138509B2 (en) | 2013-03-12 | 2018-11-27 | President And Fellows Of Harvard College | Method for generating a three-dimensional nucleic acid containing matrix |
| WO2024015766A1 (en) | 2022-07-12 | 2024-01-18 | Topogene Inc. | Scalable, submicron-resolution replication of dna arrays |
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| NL287258A (en) * | 1962-01-08 | |||
| FR88554E (en) * | 1965-07-12 | 1967-02-24 | Air Liquide | Crystalline mordenite manufacturing process |
| US3445184A (en) * | 1967-09-18 | 1969-05-20 | Norton Co | Process for producing shaped mordenite bodies |
| US3436174A (en) * | 1967-10-18 | 1969-04-01 | Norton Co | Synthetic mordenite and preparation thereof |
| JPS4810319B1 (en) * | 1968-09-10 | 1973-04-02 | ||
| US3631262A (en) * | 1970-03-31 | 1971-12-28 | Gen Electric | Linear variable gain circuit utilizing a field effect transistor |
| US4081514A (en) * | 1976-02-10 | 1978-03-28 | Zeochem Corporation | Process for producing fluidized mordenite particles |
| JPH0418614A (en) * | 1990-05-11 | 1992-01-22 | Toshiba Corp | Flowrate detecting controller |
-
1985
- 1985-09-20 JP JP60206637A patent/JPH0672011B2/en not_active Expired - Lifetime
-
1986
- 1986-09-17 CA CA000518412A patent/CA1270805A/en not_active Expired
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- 1986-09-18 DE DE8686112884T patent/DE3670276D1/en not_active Expired - Fee Related
- 1986-09-18 AU AU62909/86A patent/AU586281B2/en not_active Ceased
- 1986-09-19 DK DK450686A patent/DK166723B1/en not_active IP Right Cessation
- 1986-09-19 US US06/909,246 patent/US4861571A/en not_active Expired - Fee Related
Also Published As
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|---|---|
| DK166723B1 (en) | 1993-07-05 |
| DK450686D0 (en) | 1986-09-19 |
| EP0216312A1 (en) | 1987-04-01 |
| EP0216312B1 (en) | 1990-04-11 |
| DK450686A (en) | 1987-03-21 |
| AU6290986A (en) | 1987-03-26 |
| DE3670276D1 (en) | 1990-05-17 |
| JPS6270225A (en) | 1987-03-31 |
| US4861571A (en) | 1989-08-29 |
| AU586281B2 (en) | 1989-07-06 |
| JPH0672011B2 (en) | 1994-09-14 |
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